On Thu, May 27, 2010 at 06:16:42AM -0500, Jim Riggs wrote: > On 27 May 2010, at 5:09, Chris Sarginson wrote: > > >> Externally, users can only hit our sites at www.example.com or > >> someapp.example.com, but internally for testing, monitoring, and > >> configuration purposes, we want to be able to hit the backend servers > >> individually (i.e. web[1-3].www.example.com, > >> web[1-3].someapp.example.com). I could make 3 separate backends to handle > >> each of these and use a use_backend acl to pick based on the Host header, > >> but that seems like overkill and would be the only purpose those backends > >> serve. Is there a way to balance to a _specific_ server based on the Host > >> header (no cookies)? I know you can use a balance hdr, but that is doing > >> a hash of the header to pick the server. I need to explicitly configure > >> `Host: webX.___.example.com' to go to the backend server webX. Is that > >> doable somehow, or do I have to go the separate backend route? > > > > I find the easiest way to do this is to add an alias to each host like you > > mention, and then set up DNS records to point to that servers external IP > > address, bypassing haproxy. This way if you do start experiencing any > > issues you aren't having to debug 2 layers to find the cause - it's either > > the host or the loadbalancer. > > I had considered this, but there are two issues with it: 1) If we are > testing something, the stack now looks different (we are not going through > the load balancer), and 2) I don't want to set up SSL on the servers (it is > all handled by stunnel on the haproxy box). So, I still want all of the > traffic to go through haproxy. > > Based on the lack of other ideas, I guess I will have to go the > separate-backend-per-server route. :-\
I have still not implemented the "use-server" directive which was supposed to select a server in the group, analog to what we do with use_backend. In the mean time, some people use another technique : you set up some reqirep rules in the frontend to replace "Host: xxx" by "cookie: srv=xxx", then you just have to enable cookie-based persistence and have the correct cookies assigned to your servers. As often, this is dirty but it works ;-) Willy
